819686
Periglacial
Environments
- Distribution
- Approx 20% of
earths land
experience
periglacial conditions
- Alaska, Siberia, Canada
- Approx 20% of
earths land
experience
periglacial conditions
- Characteristics
- Long cold winters. temperatures are
rarely abouve 0 and at times may fall
below -50.
- Mean monthy temperature is less than
-3, short summers and mean annual
precipitation is less than 1000mm
- Long cold winters. temperatures are
rarely abouve 0 and at times may fall
below -50.
- PERMAFROST!!!
- Continuous
- Formed in the coldest areas
where permafrost is thick sheet
with no gaps and in areas with
temperature as low as -40C
- Formed in the coldest areas
where permafrost is thick sheet
with no gaps and in areas with
temperature as low as -40C
- Discontinuous
- permafrost is fragmented by warmer
areas like nearer rivers and the coast.
- Tend to be
warmer areas
- permafrost is fragmented by warmer
areas like nearer rivers and the coast.
- Permafrost is frozen ground, where the subsoil and underlying
rock remain frozen for two consecutive years
- Continuous
- PROCESSES
- Freeze-Thaw Action
- This process is when the
temperature changes during the day
and evening and freezes water that is
in a crack and causes it to expand
- Causes Scree slopes
- This process is when the
temperature changes during the day
and evening and freezes water that is
in a crack and causes it to expand
- Groudwater Freezing
- This occurs when its cold enough for water
within the active layer to freeze and expand
which can lead to lumps, ie. PINGOS
- This occurs when its cold enough for water
within the active layer to freeze and expand
which can lead to lumps, ie. PINGOS
- Frost Cracking
- this is similar to freeze-thaw except
the ground is already frozen
- Can lead to Ice Wedges
- this is similar to freeze-thaw except
the ground is already frozen
- Frost Heave
- This is the upward
movement of material due
to the expansion of freezing
water underneath.
- Causes stone sorted polygons
- This is the upward
movement of material due
to the expansion of freezing
water underneath.
- Nivation
- The collective set of proesses which
occur beneath snow patches . it
consists of freeze-thaw and
chemical weathering
- The collective set of proesses which
occur beneath snow patches . it
consists of freeze-thaw and
chemical weathering
- Freeze-Thaw Action
- PROCESSES
- Scree Slopes
- Largest boulders are at
the base of the slope
because they travel
further
- Largest boulders are at
the base of the slope
because they travel
further
- Pingos
- Isolated hills
containing a core of
ice.
- Isolated hills
containing a core of
ice.
- Ice Wedges
- Areas of layered
ice occupying deep
cracks.
- Areas of layered
ice occupying deep
cracks.
- Patterned Ground
- As the active layer freezes it causes
slopes which then the rocks that appear
from frost heave will roll down forming
shapes.
- As the active layer freezes it causes
slopes which then the rocks that appear
from frost heave will roll down forming
shapes.
- Scree Slopes
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